This invention generally relates to an occupant judging apparatus. More particularly, this invention pertains to an occupant judging apparatus operated based upon an output load value from a load sensor mounted on a vehicle body.
According to a vehicle provided with a known air bag for protecting a sitting occupant on a vehicle seat, an occupant judging apparatus is mounted on the vehicle seat for judging whether or not there is an occupant on the vehicle seat. One of the known occupant judging apparatus has been disclosed, for example in a Japanese Laid-open Patent Publication No.9(1997)-207638. The occupant judging apparatus includes plural load sensors and a controller. The plural load sensors are secured to plural portions for assembling the vehicle seat to a vehicle floor, respectively. The controller is employed for calculating a detected load value based upon each output load value from each load sensor and for judging whether or not there is an occupant on the vehicle seat based upon the detected load value. More specifically, the controller is further provided with an adding device and a judging process circuit. The adding device serves for adding each output load value from each load sensor so as to calculate the detected load value. The judging process circuit serves for comparing the detected load value with a predetermined load value (a judging threshold value). Accordingly, the controller can judge whether or not there is an occupant on the vehicle seat based upon a difference between the detected load value and the threshold value.
However, the following problem may occur according to the above described occupant judging apparatus, in which an only criteria for judging whether or not there is an occupant on the vehicle seat is the difference between the detected load value and the threshold value. Assuming that a child restraint system is provided on the vehicle seat, a load for fastening a seat belt may be generated to fix the child restraint system to the vehicle seat, in which the detected load value may be increased by the load for fastening the seat belt. Therefore, the occupant judging apparatus may misjudge that an adult occupant is seated on the vehicle seat.
Therefore, the above disclosed occupant judging apparatus is still susceptible of certain improvements with respect to providing an improved occupant judging apparatus for restraining an occupant misjudgment.
According to an aspect of the present invention, an occupant judging apparatus comprises load detecting means assembled to a seat body, a controller for calculating a detected load value based upon an output load value of the load detecting means and for performing an occupant judgment based upon a difference between the detected load value and a predetermined judging threshold value. The occupant judging apparatus according to the present invention further comprises human body detecting means for detecting a human body approximately in contact with the seat body, and the controller controlling the occupant judgment based upon the detected load value and the predetermined judging threshold value in response to the detecting status of the human body by the human body detecting means. The human body detecting means can be provided at a seat cushion or at a seat back.
According to another aspect of the present invention, the load detecting means includes a front load sensor for detecting a load applied to a front portion of the seat body and a rear load sensor for detecting a load applied to a rear portion of the seat body. The controller includes calculating means for calculating a ratio between an output load value of the rear load sensor and an output load value of the front load sensor, wherein the human detection is performed by the human body detecting means in response to the calculated ratio.